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Finding the Fourth Proportional to 103.78, 155.31 and 76.66

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Solution

The fourth proportional to 103.78, 155.31 and 76.66 is: 114.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.78 : 155.31 = 76.66 : x
  2. Step 2: Convert to fraction form
    103.78/155.31 = 76.66/x
  3. Step 3: Cross multiply
    103.78x = 155.31 × 76.66
  4. Step 4: Simplify right side
    103.78x = 11,906.06
  5. Step 5: Solve for x
    x = 11,906.06/103.78
  6. Step 6: Final answer
    x = 114.72

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.